Carbon monoxide (CO) inhalation is a relatively common cause of toxicity, often unnoticed due to non specific clinical presentation. Central nervous system and heart are mainly involved by mechanisms that come from the high affinity of hemo-proteins for CO, leading to hypoxic and peroxidation damage. Diagnosis may require a high grade of suspicion, oxygen supplemental therapy is the main pillar of therapy but supportive measures may be needed, as hemodynamic, respiratory and mental complications can occur. Late neuropsychiatric disorders are possible, for which early hyperbaric oxygen treatment may be of benefit.